A disk storage subsystem generally includes a plurality of hard disk assemblies (HDAs), each of which includes a disk drive assembly which is mounted on a carrier board. The HDA's are disposed in a chassis. The disk drive assembly includes a connector which interfaces with a corresponding connector on a midplane card to make necessary electrical interconnections between the respective disk drive and the midplane card, the disk drive and associated control electronics. The midplane card thus provides an electrical and mechanical interface between the connector on the HDA and other elements of the disk storage subsystem.
The connector of the midplane card is typically provided having a predetermined mechanical form factor and preselected connectors to permit electrical connection therewith. The disk drive units which connect to the midplane card, must therefore have a connector compatible with the mechanical and electrical interface of the midplane card connector.
A problem arises with respect to such disk storage subsystems in that disk drive assemblies may have different form factors and/or electrical connectors for a variety of reasons. More specifically, some standards exist for certain disk drive assemblies, such as disk drives conforming to the SCSI and SCA specifications, however, the form factors for such drives and the associated connectors are not identical. Thus, for example, if the midplane is populated with connectors having a form factor adapted for single connector attachment (SCA) drives, such will be incompatible with single computer system interface (SCSI) drives.
It is desirable to have parts sourced by a number of manufacturers for a variety of reasons. First, if a product is sole sourced and the supplier is unable to provide a device which is needed by a manufacturer, the manufacturer will be unable to produce his products and satisfy customer orders. Additionally, where products are sole sourced, or the number of suppliers are few, and the products are in high demand, there is little motivation for suppliers to offer competitive pricing.
One solution to the problems associated with the limited availability of drives having a specific interface specification is to change connectors on the midplane to adapt such midplane to the connectors associated with a different disk drive. This solution in itself poses other problems. Either selected connectors must be changed leaving the midplane card slot specific in terms of HDA type utilization or alternatively, all connectors must be changed for use with the new disk drive interface. The first alternative is undesirable in terms of sparing and manufacture since all HDA's could not be used in any chassis slot. The second alternative is undesirable as such precludes the use of any existing inventory which has an interface incompatible with the interface of the proposed replacement drives.
It would, therefore, be desirable to provide a disk storage subsystem having a single midplane card which can accept disk drives having different disk drive connectors.